Upon creating a storage space, certain fundamental properties are locked in place. These fundamental properties include the provisioning type (thin or fixed), the resiliency type (simple, mirror, or parity), the number of columns the storage space striping requires, and the striping interleave.

After creating a storage space, you can change properties that do not affect fundamental characteristics, such as the size of the storage space and its name.

Two ways of provisioning virtual disks:

  • Fixed provisioning The size of the virtual disk is the actual amount of physical storage space allocated from the pool.

  • Thin provisioning The size of the virtual disk represents the maximum amount of physical storage space that can be allocated from the pool. No space is actually used, however, until data is stored on a volume on the virtual disk, and the amount of space used will grow or shrink as data is written to or deleted from the disk.

Note: To cluster Storage Spaces, all storage spaces in the storage pool must use fixed provisioning.

Ref: http://social.technet.microsoft.com/wiki/contents/articles/11382.storage-spaces-frequently-asked-questions-faq.aspx#What_types_of_drives_can_I_use_with_Storage_Spaces